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client go自定义控制器

油腻中年李大鹅 人气:0

介绍

我们已经知道,Service对集群之外暴露服务的主要方式有两种:NodePort和LoadBalancer,但是这两种方式,都有一定的缺点:

基于这种现状,Kubernetes提供了Ingress资源对象,Ingress只需要一个NodePort或者一个LB就可以满足暴露多个Service的需求。

客户端首先对 域名 执行 DNS 解析,得到 Ingress Controller 所在节点的 IP,然后客户端向 Ingress Controller 发送 HTTP 请求,然后根据 Ingress 对象里面的描述匹配域名,找到对应的 Service 对象,并获取关联的 Endpoints 列表,将客户端的请求转发给其中一个 Pod。

本文我们来使用client-go实现一个自定义控制器,通过判断serviceAnnotations属性是否包含ingress/http,如果包含则创建ingress,如果不包含则不创建。而且如果存在ingress则进行删除。

具体实现

首先我们创建项目。

$ mkdir ingress-manager && cd ingress-manager
$ go mod init ingress-manager
# 由于控制器部分的内容比较多,将它们单独放到pkg目录下
$ mkdir pkg
# 最终项目目录结构如下
.
├── go.mod
├── go.sum
├── main.go
└── pkg
    └── controller.go

接着我们来实现controller部分:

package pkg
import (
	"context"
	apiCoreV1 "k8s.io/api/core/v1"
	netV1 "k8s.io/api/networking/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metaV1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	informersCoreV1 "k8s.io/client-go/informers/core/v1"
	informersNetV1 "k8s.io/client-go/informers/networking/v1"
	"k8s.io/client-go/kubernetes"
	coreV1 "k8s.io/client-go/listers/core/v1"
	v1 "k8s.io/client-go/listers/networking/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/util/workqueue"
	"reflect"
	"time"
)
const (
	workNum  = 5  // 工作的节点数
	maxRetry = 10 // 最大重试次数 
)
// 定义控制器
type Controller struct {
	client        kubernetes.Interface
	ingressLister v1.IngressLister
	serviceLister coreV1.ServiceLister
	queue         workqueue.RateLimitingInterface
}
// 初始化控制器
func NewController(client kubernetes.Interface, serviceInformer informersCoreV1.ServiceInformer, ingressInformer informersNetV1.IngressInformer) Controller {
	c := Controller{
		client:        client,
		ingressLister: ingressInformer.Lister(),
		serviceLister: serviceInformer.Lister(),
		queue:         workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "ingressManager"),
	}
	// 添加事件处理函数
	serviceInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    c.addService,
		UpdateFunc: c.updateService,
	})
	ingressInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		DeleteFunc: c.deleteIngress,
	})
	return c
}
// 入队
func (c *Controller) enqueue(obj interface{}) {
	key, err := cache.MetaNamespaceKeyFunc(obj)
	if err != nil {
		runtime.HandleError(err)
	}
	c.queue.Add(key)
}
func (c *Controller) addService(obj interface{}) {
	c.enqueue(obj)
}
func (c *Controller) updateService(oldObj, newObj interface{}) {
	// todo 比较annotation
	// 这里只是比较了对象是否相同,如果相同,直接返回
	if reflect.DeepEqual(oldObj, newObj) {
		return
	}
	c.enqueue(newObj)
}
func (c *Controller) deleteIngress(obj interface{}) {
	ingress := obj.(*netV1.Ingress)
	ownerReference := metaV1.GetControllerOf(ingress)
	if ownerReference == nil {
		return
	}
	// 判断是否为真的service
	if ownerReference.Kind != "Service" {
		return
	}
	c.queue.Add(ingress.Namespace + "/" + ingress.Name)
}
// 启动控制器,可以看到开了五个协程,真正干活的是worker
func (c *Controller) Run(stopCh chan struct{}) {
	for i := 0; i < workNum; i++ {
		go wait.Until(c.worker, time.Minute, stopCh)
	}
	<-stopCh
}
func (c *Controller) worker() {
	for c.processNextItem() {
	}
}
// 业务真正处理的地方
func (c *Controller) processNextItem() bool {
	// 获取key
	item, shutdown := c.queue.Get()
	if shutdown {
		return false
	}
	defer c.queue.Done(item)
  // 调用业务逻辑
	err := c.syncService(item.(string))
	if err != nil {
    // 对错误进行处理
		c.handlerError(item.(string), err)
		return false
	}
	return true
}

func (c *Controller) syncService(item string) error {
	namespace, name, err := cache.SplitMetaNamespaceKey(item)
	if err != nil {
		return err
	}
	// 获取service
	service, err := c.serviceLister.Services(namespace).Get(name)
	if err != nil {
		if errors.IsNotFound(err) {
			return nil
		}
		return err
	}
	// 新增和删除
	_, ok := service.GetAnnotations()["ingress/http"]
	ingress, err := c.ingressLister.Ingresses(namespace).Get(name)
	if err != nil && !errors.IsNotFound(err) {
		return err
	}
	if ok && errors.IsNotFound(err) {
		// 创建ingress
		ig := c.constructIngress(service)
		_, err := c.client.NetworkingV1().Ingresses(namespace).Create(context.TODO(), ig, metaV1.CreateOptions{})
		if err != nil {
			return err
		}
	} else if !ok && ingress != nil {
		// 删除ingress
		err := c.client.NetworkingV1().Ingresses(namespace).Delete(context.TODO(), name, metaV1.DeleteOptions{})
		if err != nil {
			return err
		}
	}
	return nil
}
func (c *Controller) handlerError(key string, err error) {
	// 如果出现错误,重新加入队列,最大处理10次
	if c.queue.NumRequeues(key) <= maxRetry {
		c.queue.AddRateLimited(key)
		return
	}
	runtime.HandleError(err)
	c.queue.Forget(key)
}
func (c *Controller) constructIngress(service *apiCoreV1.Service) *netV1.Ingress {
	// 构造ingress
	pathType := netV1.PathTypePrefix
	ingress := netV1.Ingress{}
	ingress.ObjectMeta.OwnerReferences = []metaV1.OwnerReference{
		*metaV1.NewControllerRef(service, apiCoreV1.SchemeGroupVersion.WithKind("Service")),
	}
	ingress.Namespace = service.Namespace
	ingress.Name = service.Name
	ingress.Spec = netV1.IngressSpec{
		Rules: []netV1.IngressRule{
			{
				Host: "example.com",
				IngressRuleValue: netV1.IngressRuleValue{
					HTTP: &netV1.HTTPIngressRuleValue{
						Paths: []netV1.HTTPIngressPath{
							{
								Path:     "/",
								PathType: &pathType,
								Backend: netV1.IngressBackend{
									Service: &netV1.IngressServiceBackend{
										Name: service.Name,
										Port: netV1.ServiceBackendPort{
											Number: 80,
										},
									},
								},
							},
						},
					},
				},
			},
		},
	}
	return &ingress
}

接下来我们来实现main:

package main
import (
	"ingress-manager/pkg"
	"k8s.io/client-go/informers"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
)
func main() {
	// 获取config
	// 先尝试从集群外部获取,获取不到则从集群内部获取
	var config, err = clientcmd.BuildConfigFromFlags("", clientcmd.RecommendedHomeFile)
	if err != nil {
		clusterConfig, err := rest.InClusterConfig()
		if err != nil {
			panic(err)
		}
		config = clusterConfig
	}
	// 通过config创建 clientSet
	clientSet, err := kubernetes.NewForConfig(config)
	if err != nil {
		panic(err)
	}
	// 通过 client 创建 informer,添加事件处理函数
	factory := informers.NewSharedInformerFactory(clientSet, 0)
	serviceInformer := factory.Core().V1().Services()
	ingressInformer := factory.Networking().V1().Ingresses()
	newController := pkg.NewController(clientSet, serviceInformer, ingressInformer)
	// 启动 informer
	stopCh := make(chan struct{})
	factory.Start(stopCh)
	factory.WaitForCacheSync(stopCh)
	newController.Run(stopCh)
}

测试

首先创建deploy和service:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  selector:
    matchLabels:
      app: my-nginx
  template:
    metadata:
      labels:
        app: my-nginx
    spec:
      containers:
        - name: my-nginx
          image: nginx:1.17.1
          ports:
            - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: my-nginx
  labels:
    app: my-nginx
spec:
  ports:
    - port: 80
      protocol: TCP
      name: http
  selector:
    app: my-nginx

创建完成后进行查看:

$ kubectl get deploy,service,ingress
NAME                              READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/my-nginx          1/1     1            1           7m
NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1      <none>        443/TCP   78d
service/my-nginx     ClusterIP   10.105.32.46   <none>        80/TCP    7m

上面的命令我分别获取deploy,service,ingress,但是只获取到了deployservice,这符合我们的预期。接着我们给service/m-nginx中的annotations添加ingress/http: nginx

$ kubectl edit service/my-nginx
apiVersion: v1
kind: Service
metadata:
  annotations:
    ingress/http: nginx
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"my-nginx"},"name":"my-nginx","namespace":"default"},"spec":{"ports":[{"name":"http","port":80,"protocol":"TCP"}],"selector":{"app":"my-nginx"}}}
      ......
service/my-nginx edited

重新进行查看:

$ kubectl get deploy,service,ingress
NAME                              READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/demo-deployment   1/1     1            1           41d
deployment.apps/my-nginx          1/1     1            1           11m
NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1      <none>        443/TCP   78d
service/my-nginx     ClusterIP   10.105.32.46   <none>        80/TCP    11m
NAME                                 CLASS    HOSTS         ADDRESS   PORTS   AGE
ingress.networking.k8s.io/my-nginx   <none>   example.com             80      19s

接着我们再来测试下,将ingress/http: nginx注释掉,看看ingress是否会自动删除:

$ kubectl get deploy,service,ingress
NAME                              READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/demo-deployment   1/1     1            1           41d
deployment.apps/my-nginx          1/1     1            1           19m
NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1      <none>        443/TCP   78d
service/my-nginx     ClusterIP   10.105.32.46   <none>        80/TCP    19m

我们发现和我们预期的效果一样。

如果service被删除了,ingress肯定也是不会存在的。这个这里就不多演示了。有兴趣可以自行测试下。

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